SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '98873f8cbd6ba863b520e69d8b880d0b281539da7b4f23168243382db204c0ad' 
  AND token = 'KcwjXQ5IFHHgb/QziB/sq1I+6M/KekZmnydTO1xM4cE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}